Nitro amines and process for preparing them



Patented Aug. 23, 1949 NITRO AMINES AND PROCESS FOR PREPARING THEMMurray Senkus, Terre Haute, Ind., assignor to Commercial SolventsCorporation,

Terre Haute,

Ind., a corporation of Maryland No Drawing. Application February 26,1945, Serial No. 579,895

6 Claims.

My invention relates to new nitro amines and to a process for thepreparation thereof, Specifically, these new compounds may berepresented by the following structural formula:

in which R represents aralkyl and R and R represent lower alkyl groups.

As examples of nitro amines coming within the scope of the above formulathere may be mentioned the following: N-(Z-nitroisobutyl) benzylamine,2-nitro-2-methyl-5-phenyl-4-azoheXane, and the like.

This application is a continuation-in-part of my co-pending application,Serial No. 455,931 filed August 24, 1942, now abandoned.

Prior investigators in this field have found that primary nitroparaffinswould react with N-(hydroxymethyDdialkylamines; however, they alsoarrived at the conclusion, while making the aforesaid discovery, thatN-(hydroxymethyhmonm alkylamines would not react with primarynitroparafins, and that secondary nitroparaffins would neither reactwith N-hydroxymethyl mononor dialkylamines under any of the experimentalconditions which they had found to be effective in condensing a primarynitroparafiin with N (hydroxymethyl) dialkylamines. workers also were ofthe opinion, in view of their own experimental results, that neitherprimary nor secondary nitroparafiins would react with condensationproducts derivable from formaldehyde and ammonia, formaldehyde andprimary alkylamines, formaldehyde and aniline, formaldehyde anddiphenylamine, formaldehyde and N-methylaniline, and numerous otherproducts of similar structure prepared from higher molecular weightaldehydes, and primary or secondary amines.

Contrary to that which would normally be expected in view of the aboveprior art findings, however, I have discovered that nitro amines of thetype described may be prepared by reacting formaldehyde with a primaryor secondary amine in which the N substituents are cyclic groupsattached to the amino nitrogen through a CH2 group to form thecorresponding N-(hydroxymethyl) mono-, or diamine, which is in turnreacted with an equimolecular amount of a secondary nitroparafiin toproduce a nitro amine of the type represented by the'generic formulagiven above.

A modification of the above procedure may fre- Previous Gil quently beemployed to advantage, and consists of reacting the desired amine with asuitable nitro alcohol. A solvent may be used if desired, but in generalit will be found that a homogeneous solution can be obtained byagitating the mixture of amine and nitro alcohol. The products, producedby this process, are identical with those synthesized by the firstmentioned method; however, the mechanism of the reaction in its initialstages is materially different from that involved in the firstprocedure. In this connection, it has been observed that primary nitroalcohols, when in the presence of a substance appreciably basic incharacter, decompose into formaldehyde and the nitroparafi'in from whichthey were derived, and in instances where the basic material happens tobe a primary or secondary amine, the liberated formaldehyde reactstherewith to form a N- (hydroxymethyl) -amine compound which then reactswith the nitroparaffin, produced by the decomposition of the nitroalcohol, in the same manner as described in the first procedure. Thecourse of the reaction involved may be readily illustrated by thefollowing series of equations:

NHydroxymethyl-R amine Nitroparafiin Desired nitro amine From anexamination of the above series of equations, it will be evident thatalthough the starting materials are difierent from those used in theprocess first described, both procedures may be considered equivalentsof one another, since the compounds employed as starting materials inthe first process are produced as intermediates in the second, afterwhich said intermediates react in a manner identical with the mechanisminvolved in the reaction forming the basis of the first mentionedmethod. Therefore, it is to be specifically understood that the appendedprocess claims include both methods.

The preparation of these nitro amines by either of the above-mentionedmethods, is preferably effected at temperatures of from about 25-30 C.Temperatures above this range may be used, but

in doing so care should be exercised to avoid temperatures which causethe formaldehyde to be volatilized from the reaction mixture. In. somecases it may be desirable to carry out the reaction in a high pressurereaction vessel. Under such circumstances, substantially highertemperatures may be utilized without loss of formaldehyde, anddecomposition of the reactants, or the reaction products,

The amines which may be employed in preparing these new compositions ofmatter are represented by the formula:

wherein R represents aralkyl. As examples of such amines, there may bementioned benzylamine, l-phenyl-l-ethylamine, and the like.

Nitroparafiins that are operative in my process may be represented bythe following formula:

ployed instead of a nitroparaflin and formaldehyde, the following areexamples of typical nitro alcohols which may be utilized:2-nitro-2-methyl- I-propanol, 2-nitro-2-methyl-1-butanol, 2-nitro-Z-ethyl-l-butanol, and the like.

The examples which follow are illustrative of the-various types of nitroamines that come within the scope of the present invention. The examplesare likewise illustrative of the procedures by which said products maybe synthesized. It is tOf be specifically understood, however, that thefollowing examples in no way limit the scope of my invention withrespect to either the product or the process, since I have found thatthe reaction involved is very general in nature, and will occur, underthe conditions described when reacting substantially any secondarynitroparaffin with a primary amine of the various types enumeratedabove,

Example '1 One mole of benzylamine and one mole of 2-nitro-2-methyl-l-propanol were placed in a glassstoppered reactionvessel and the mixture was shaken until it had become homogeneous. Themixture was allowed to stand at about 30 C. Water began to separateafter about hours. When the separation of water was substantiallycomplete the crude product, N -(2-nitroisobutyl) benzylamine, wasseparated from the lower aqueous layer and was fractionated. Fractionaldistillation resulted in 156 parts of product corresponding to aconversion of 75%. The product had a nitrogen content of 13.59% ascompared to a calculated value of 13.46%, a boiling point of 130-133 C,at 2 mm. and 11 of 1.5178 and Example II One mole ofl-phenyl-l-ethylamine and one mole of 2-nitro-2-methyl-l-propanol wereplaced in a glass-stoppered reaction vessel and the mixture was shakenuntil it had become homogeneous. The mixture was allowed to stand atabout 30 C. Water began to separate after about 10 10 hours. When theseparation of water was substantially complete the crude product, 2-nitro-2-methyl-5-phenyl-4-azahexane, was separated from the loweraqueous layer and was fractionated. Fractional distillation resulted in166 parts of product corresponding to a conversion of 75%. The producthad a nitrogen content of 12.85% as compared to a calculated value of12.61%, a boiling point of 121-124: C. at .8 mm. and 11 of 1.5080 and iof 1.0809.

Example III 101 parts of tetrahydrofurfurylamine were placed in areaction vessel fitted with a stirrer, thermometer, and dropping funnelthen 75 parts of 35% aqueous formaldehyde were added to the amine duringagitation; The mixture was externally cooled and the temperaturemaintained below 50 C., then parts of Z-nitropropane were added to thereaction mixture and the mixture stirred for hour when 500 parts or"ethyl ether were added during stirring. Two layers separated and thenon-aqueous layer was separated and distilled. Distillation resulted in104 parts of N-( nitroisobutyl) tetrahydrofurfurylamine corresponding toa conversion of 75%. The product had a boiling point of 105C. at 0.7 mm.

This example illustrates the embodiment of my process whereinformaldehyde is added to the reaction zone rather than being produced insitu through the decomposition of a nitroalcohol. In this embodiment ofmy process a condensation reaction is caused between formaldehyde, aprimary amine and a nitroalkane, as described previously.

The nitro amines of my invention are in general either colorless liquidsor white waxy solids. The loW-molecular-weight nitro amines possesscharacteristic pungent odors, whereas the highmolecular-weightnitroamines are relatively odorless. The nitro amines are soluble inether, methanol, and benzene, but are insoluble in water.

f JEI-O-R t.

at temperatures above about 25 C. but below those causing anysubstantial loss of formaldehyde from the mixture and recovering theresulting nitroamine having the formula:

r R -NHCHzCR wherein R represents an aralkyl group and R and R representlower alkyl groups.

2. The process of claim 1 wherein the formaldehyde and nitroalkane inthe reaction mixture propanol at temperatures above about 25 C. but 15below those causin any substantial loss of formaldehyde from the mixtureand recovering the resultin N -(2-nitroisobutyl) benzylamine therebyformed.

5. Nitroamines having the following structural formula:

wherein R represents aralkyl, and R and R. represent lower alkyl groups.

6. N (2-nitroisobuty1) benzylamine.

MURRAY SENKUS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,253,082 McNally et a1 Aug. 19,1941 2,292,212 Dickey et al Aug. 4, 1942 2,206,885 Dickey et a1 July 9,1940 OTHER REFERENCES Chemical Abstract, 1938, page 494.

